1.使用touchlistener時，如果需要判斷MotionEvent.ACTION_DOWN或者MotionEvent.ACTION_UP時，需要對目標控件設置
setLongClickable(true);才有效。
2.Margin:用來設置一個元素所占空間的邊緣到相鄰元素之間的距離.
Padding:用來設置元素內容到元素邊界的距離。
3.Note: When installing JDK on Windows, the default is to install in the "Program Files" directory. This location will cause ant to fail, because of the space. To fix the problem, you can specify the JAVA_HOME variable like this: set JAVA_HOME=c:"Prora~1"Java". The easiest solution, however, is to install JDK in a non-space directory, for example: c:"java"jdk1.6.0_02.
4.APK簽名的另一種方法：
When you publish an app on the market, you need to sign it with a personal private key. The typical way to generate the key is with keytool, and then sign it with jarsigner. But this is generally a pain ;)
The git source tree has a SignApk.jar utility that is easier to use to sign apks. You can use the following three steps to generate a key and certificate that can be used with SignApk.jar
openssl genrsa -out key.pem 1024
openssl x509 -req -days 9999 -in request.pem -signkey key.pem -out certificate.pem
openssl pkcs8 -topk8 -outform DER -in key.pem -inform PEM -out key.pk8 -nocrypt
Then, you can sign an apk using the SignApk.jar tool and the key.pk8 and certificate.pem files you created
java -jar SignApk.jar certificate.pem key.pk8 Application.apk Application_signed.apk
Retrieved from "http://android-dls.com/wiki/index.php?title=Generating_Keys"
5.E/AndroidRuntime(10851): java.lang.SecurityException: Permission
> Denial: starting Intent { act=android.intent.action.SEARCH
> cmp=com.amazon.mp3/.client.activity.SearchActivity (has extras) } from
> ProcessRecord{43cd17f0 10851:com.myTestApp/10054} (pid=10851,
> uid=10054) requires null
"requires null" means that there is no permission, but that particular
component is not exported from the .apk, so -nobody- else can use it.
原因在于要調用的activity在另外一個app里，不允許顯示的調用。
解決：
使用隱士intent或簽名
6.查看android 自帶app的簽名
在android.mk下有一行如LOCAL_CERTIFICATE := platform，那么簽的就是platform的名。
簽名文件位置：android1.6r1/build/target/product/security